1. Field of the Invention
The present invention relates to a printing apparatus, a printing apparatus control method, and a storage medium storing a program thereof.
2. Description of the Related Art
Recently, printing apparatuses which perform mass printing often use a stacker capable of discharging, stacking, and holding a large number of printed materials such as 5,000 or 10,000 sheets. During mass printing, the state of the printing apparatus may change, and the print finish may differ from what the user wants. For example, when printed materials are copied a plurality of times, the state of the printing apparatus changes and the printing tint of even the same page changes as represented by pages 1501 and 1502 shown in FIG. 10. When printing results are stacked on the stacker, the physical structure of the stacker makes it difficult to confirm the printing results stacked on the stacker without stopping printing. This is because the stacker is comprises housing and the user cannot confirm printing results unless he opens the front door, stops printing, and takes out the contents.
To solve this, Japanese Patent Laid-Open No. 2005-144797 discloses a printing system having a sample printing function. When the user issues a sample printout instruction during printing, the sample printing function prints, on another sheet, an image to be printed on the next sheet, and discharges the printed sheet onto a discharge unit such as an escape tray. With this function, the user can easily inspect a printed material without stopping printing in the printing apparatus.
However, a conventional printing apparatus cannot easily specify a sheet having undergone sample printing out of sheets successively stacked on the stacker.
For example, the user cannot determine, among a large number of stacked sheets, the position of a sheet printed in almost the same tint as that of a sheet discharged onto the escape tray using the sample printing function. Assume that sample printing is executed for the 1,500th sheet when printing 2,000 sheets, and the user checks the sample printing result discharged onto the escape tray and detects a change of the tint. Even while the user confirms the sample printing result, the printing apparatus keeps stacking sheets in the stacker in order to prevent a decrease in productivity. Thus, the user cannot easily specify later the position of a sheet among stacked sheets on which the tint of the sheet printed by sample printing has changed.